Figure 7.

Relationships between age, Aβ deposition, brain function, and cognition. Each brain image represents the projection of data from Figures 2, 3, and 5 onto the inflated cortical surface of the right hemisphere along with brain function and behavior relationships as shown in Figure 4a, and d. The present findings suggest differential age and Aβ-related changes in regional activity and MTL-seeded connectivity during episodic encoding. Age (in the absence of Aβ) is associated with failure to engage brain regions crucial to encoding new information, such as MTL structures, and also with reduced task-independent connectivity across brain regions. These changes are accompanied by increased task-dependent functional connectivity contributing to preserved EM performance in older adults. Elevated Aβ deposition, on the other hand, recruits more local activity in conjunction with the failure to engage task-dependent functional coupling to perform EM encoding equivalently to older adults without Aβ deposition. This increased regional activity is not associated with memory function. Increased regional activity and task-independent connectivity for YOUNG compared with PIB− OLD are shown in green and blue, respectively, while the overlapping regions are shown in cyan; increased task-dependent connectivity for PIB− OLD compared with either YOUNG or PIB+ OLD are shown in yellow; increased regional activity for PIB+ OLD compared with PIB− OLD is shown in orange/red.